This invention relates to novel cephalosporin derivatives, which are useful intermediates in the isolation of cephalosporin C from fermentation broths and in the preparation of 7-aminocephalosporanic acid, to a process for the preparation of the said derivatives from fermentation broths containing cephalosporin C, and to their subsequent conversion into 7-aminocephalosporanic acid.
7-Aminocephalosporanic acid (hereinafter referred to as 7-ACA), which has the formula: ##SPC1##
Is useful as an intermediate in the preparation of many semi-synthetic cephalosporanic acid antibacterial agents. Most 7-ACA is produced from cephalosporin C, which has the formula: ##SPC2##
Either by chemical degradation (e.g. as described in U.S. Pat. Nos. 3,124,576, 3,188,311 and 3,234,223) or by enzymatic hydrolysis of the side-chain (e.g. as described in French Pat. No. 1,357,977).
Cephalosporin C is produced by fermentation. However, its highly polar nature renders it very soluble in water, and it is very difficult to recover it from the fermentation broth by solvent extraction. The recovery precedure most generally used at present involves the adsorption of the crude cephalosporin C from the fermentation broth onto a suitable adsorbant, for example, charcoal or an ion exchange resin, followed by elution, concentration and precipitation at the isoelectric point, or by salt formation (see, for example, U.S. Pat. No. 3,094,527). The complexity of this multi-step process, and the low yields obtained thereby, render it unfavourable for the production of cephalosporin C and hence of 7-ACA.